Trees: sucking up the carbon

Forests in many regions are becoming larger carbon sinks thanks to higher density, US and European researchers say in a new report. In Europe and North America, increased density significantly...click to enlarge

Forests in many regions are becoming larger carbon sinks thanks to higher density, U.S. and European researchers say in a new report.

In Europe and North America, increased density significantly raised carbon storage despite little or no expansion of forest area, according to the study, led by Aapo Rautiainen of the University of Helsinki, Finland, and published in the online, open-access journal PLoS One.

Even in the South American nations studied, more density helped maintain regional carbon levels in the face of deforestation.

The researchers analyzed information from 68 nations, which together account for 72 percent of the world’s forested land and 68 percent of reported carbon mass. They conclude that managing forests for timber growth and density offers a way to increase stored carbon, even with little or no expansion of forest area.

“In 2004 emissions and removals of carbon dioxide from land use, land-use change and forestry comprised about one fifth of total emissions. Tempering the fifth by slowing or reversing the loss of carbon in forests would be a worthwhile mitigation. The great role of density means that not only conservation of forest area but also managing denser, healthier forests can mitigate carbon emission,” says Rautiainen.

Co-author Paul E. Waggoner, a forestry expert with Connecticut’s Agricultural Experiment Station, says remote sensing by satellites of the world’s forest area brings access to remote places and a uniform method. “However, to speak of carbon, we must look beyond measurements of area and apply forestry methods traditionally used to measure timber volumes.”

“Forests are like cities – they can grow both by spreading and by becoming denser,” says co-author Iddo Wernick of The Rockefeller University’s Program for the Human Environment.

IMAGE:Forests in many regions are becoming larger carbon sinks thanks to higher density, US and European researchers say in a new report. In Europe and North America, increased density significantly…Click here for more information.

The authors say most regions and almost all temperate nations have stopped losing forest and the study’s findings constitute a new signal of what co-author Jesse Ausubel of Rockefeller calls “The Great Reversal” under way in global forests after centuries of loss and decline. “Opportunities to absorb carbon and restore the world’s forests can come through increasing density or area or both.”

To examine how changing forest area and density affect timber volume and carbon, the study team first focused on the United States, where the U.S. Forest Service has conducted a continuing inventory of forest area, timberland area and growing stock since 1953.

They found that while U.S. timberland area grew only 1 percent between 1953 and 2007, the combined national volume of growing stock increased by an impressive 51 percent. National forest density increased substantially.

For an international perspective, the research team examined the 2010 Global Forest Resources Assessment compiled by the UN Food and Agriculture Organization (FAO), which provides consistent figures for the years 1990 to 2010.

The data reveal uncorrelated changes of forest area and density. Countries in Africa and South America, which lost about 10 percent of their forest area over the two decades, lost somewhat less carbon, indicating a small rise in forest density.

In Asia during the second decade of the study period, density rose in 10 of the region’s 21 countries. Indonesia’s major loss of density and sequestered carbon, however, offset any gain in carbon storage in other Asian nations.

Europe, like the U.S., demonstrated substantial density gains, adding carbon well in excess of the estimated carbon absorbed by the larger forested area.

Says study co-author Pekka Kauppi, of the University of Helsinki, Finland, “With so much bad news available on World Environment Day, we are pleased to report that, of 68 nations studied, forest area is expanding in 45 and density is also increasing in 45. Changing area and density combined had a positive impact on the carbon stock in 51 countries.”

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33 thoughts on “Trees: sucking up the carbon”

More Co2 in the atmosphere promotes more growth and causes more CO2 to be absorbed during growth cycles but also increases the amount of plant material to decay during dormant periods. This increases the natural contribution to the Carbon cycle both sink and source.

The reason we never ratified Kyoto is because in the draft protocol there were carbon “credits” for forest expansion. Then when it turned out the U.S. was responsible for so much forest expansion both here and abroad and that the forest credits would allow us to emit as much more carbon as we wanted and just plant more trees to nullify it. So in the final version of the protocol the forestation credits were vastly reduced and Bill Clinton said “thanks but no thanks, we’ll just continue planting trees and y’all can go pound sand”.

If the woodlands are denser, then there is more transpiration, more heat moving upwards carried away by the extra water vapor. We’re familiar with the Urban Heat Island (UHI) effect driving up surface temperatures. Do thicker woodlands lead to an increased Forest Cool Area effect? We already see this in the Amazon rainforest, which ends up generating its own thunderstorms providing further cooling during the day. Will these denser woodlands worldwide significantly lower surface air temperatures on land?

Interesting – as far as it goes. But . . .
I have volunteered for the local county conservation district in their annual plant sale. This started about 15 years ago and has grown so large that they now use a crew from AmeriCorps. My first stint was about 12 years ago, and I did 10 seasons before the volume overwhelmed us aging volunteers.
The first year I planted ten Ponderosa Pines along the driveway and another 20 trees of different variety. The pines were about a foot tall and pencil thin. Those first trees are now about 8 inches in diameter at belt height. I’ve continued to plant these and other tree species every year. Via help from all the county conservation districts throughout the State of Washington, hundreds of folks are doing the same and turning city lots and mini-ranches (10 to 20+ acres) into wooded parcels – parcels that were mostly treeless 20 or 30 years ago. Many riparian areas (I have about 10 acres of such) are now being protected from grazing and the trees and woody shrubs have filled in and are much healthier – encroaching on the pasture.

I’ve read that wood is about half carbon by weight. I do not sense in the report presented that the folks were including the sorts of additions to the carbon depository such as I have described. If not, the carbon sink is larger than they describe and expanding.

All I know is there’s a hell of a lot of trees out there. Most people don’t realize how many trees there are because people don’t live in forests. But just looking at what I can see from the roads and and around houses there are a lot of trees. If you fly in a small plane, small because jets fly too high, you’ll see how many trees there are. Its quite a lot.

Forest density is not exactly a no-brainer for increased CO2 uptake. When forest density increases above 10x historic levels, trees compete for water and light. Biodiveristy decreases in the dark forest; the interface between forest and meadow is where biodiversity peaks. The trees that survive under these sub-optimal conditions are often sick. They do not grow efficiently. Consequently, CO2 uptake is not even close to the maximum per acre.

In a dense forest, the fire hazard grows to explosive conditions. The CO2 released from a big fire is just the beginning. It is estimated that 3x that amount is released as the dead trees rot. Harvesting the dead trees would avoid that outcome. Naturally, these harvests are blocked. Well meaning, and well-programmed urban environmental zealots cause these problems by funding enviro ‘hands-off’ forestry policies backed up by lawsuits.

Many of our forests are now 10-fold higher density than pre-european forests. Native people kept down mid-level fuels and maintained meadows through the use of fire. However, these fires did not burn the way our forests do now. Historic fires burned low to the ground. Now, big fires convert soil to hydrophobic clay, and kill everything.

Forests restored to historic conditions would reduce evapotranspiration and result in more water for fish, agriculture, and human consumption. Lower density forests can in fact be more productive than overgrown forests with sick trees. Regular tree harvests do not destory the land or the water, certainly not the way big fires do. It can take hundreds of years for a forest to recover if the soil is destroyed by a modern unnaturally hot fire.

Sorry, Bambi is not real. Real deer die in fires caused by 100 years of bad policy. Real deer also are hit by cars. We allowed trees to choke high meadows, driving deer to forage in inhabited areas. Restore the forest, restore the meadows; in return you get increased biodiveristy, smaller fires, and a lot more water.

Says study co-author Pekka Kauppi, of the University of Helsinki, Finland, “With so much bad news available on World Environment Day, we are pleased to report that, of 68 nations studied, forest area is expanding in 45 and density is also increasing in 45. Changing area and density combined had a positive impact on the carbon stock in 51 countries.”

We’re all gonna have to work harder to feed the biosphere. Everybody detune that V-8, lay in a cement patio and throw another log on the fire.

so you increase the supply of one of the basic plant nutrients you find that the plants grow better; perhaps they could try increasing things like water, or nitrates or phosphates, they might increase plant growth too. Shocking.

Rock! Rock! Rock! The only long-term storage of CO2 occurs when it ends up as limestone or organic-rich rock. Yes those trees can become coal but the process takes millenia. All any of us can do is arm-wave in the short-term. No one can predict what CO2 today will end up permanently removed from the geosphere, in amounts sufficient to make a difference.

Rock! Rock! Rock! The only long-term storage of CO2 occurs when it ends up as limestone or organic-rich rock. Yes those trees can become coal but the process takes millenia. All any of us can do is arm-wave in the short-term. No one can predict what CO2 today will end up permanently removed from the geosphere, in amounts sufficient to make a difference.
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Kind of a catch 22, isn’t it? We all love trees, but in the end, trees will give up the CO2, for the most part. The more trees, the more atmospheric CO2. Oh, the irony!!! The solution, of course, is to live in a barren land devoid of plant-life! …………….. Or there may be another mechanism of which we’re not aware……….

So we emitted this vast volume of extra plant food, the trees got denser, people settled in the new thick forests, and the fires are now more intense and destructive.
Sounds more like Global Growing and Forest Glowing.
We could do a LOT better at managing our new tree farms, but, as KDKnoebel says, the Greens won’t let anybody do anything of the kind.
Of note: You don’t hear of people tying themselves to trees anymore. Now they just tie the whole darn forest up in legal knots.
Sad, isn’t it? Our new tree farms are destined to go up in Green smoke.

@ kadaka “If the woodlands are denser, then there is more transpiration, ”

Not necessarly… there was a study that showed that the leaves on the trees actually decrease the density of stomate on the back of the leaves in a CO2 increased atmosphere, thus reducing transpiration… ie becoming more efficient with water. Nature is clever, ya see.

At around 250ppm CO2 the stomate are packed tight, which makes sense when you consider that most plant have trouble breathing below about 200ppm CO2.

Ie.. we have been just above plant subsistence levels of CO2 for the last million or so years, maybe because the ultra-lush plant growth died and was buried as it ran out of CO2 (look at the long historic levels of CO2. you will see that the large concentrations of CO2 many million years ago suddenly dropped at around the time plant life probably took off, dropping rapidly to bare subsistence levels)

I always wondered if agricultural cultivation of vast barren lands by man, going on for thousands of years, has ever been taken into account as an important CO2-absorbing and climate-moderating factor by those who, like IPCC and Dr. Ira Glickstein, are so fond of playing games with the formulas.

It may very well be that human activity, in the final reckoning, is more beneficial than it is destructive, as opposed to the purely hypothetical “natural state” of the planet.

Dr Patrick Moore (PhD in Ecology) comments extensively on forrest management and biodiversity in his last book. Presenting slightly more balanced views comparing to those of Hoser here above.
I think that societies and nations can afford environment protection once they become sufficiently rich, with developed economies. Poverty kills the environment. One may have a look on the history and timing of laws protecting air, water, soil – rich countries introduced it first, quite long time ago. Poor people – having agriculcture of low productivity or pastoral economy – are capable of putting quite a high load on their environment.

We could do a LOT better at managing our new tree farms, but, as KDKnoebel says, the Greens won’t let anybody do anything of the kind.

I’ve likely made that observation before about forests in general, and it is self-evident to many, but for this article I believe the credit goes to Hoser.
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From Andy G55 on June 6, 2011 at 9:47 pm:

@ kadaka “If the woodlands are denser, then there is more transpiration, ”

Not necessarly… there was a study that showed that the leaves on the trees actually decrease the density of stomate on the back of the leaves in a CO2 increased atmosphere, thus reducing transpiration… ie becoming more efficient with water. Nature is clever, ya see.

Not necessarily, and I knew that, but the difference should get swamped out with sufficient increases in woodland density. For example, it doesn’t seem likely you could support five times the density with the same amount of water consumption.

Also unmanaged woodland areas tend to grow rather thick rather fast. I’m on the edge of a forest, and from when my parents built this house a half century ago they have photos showing this whole hilltop area was cleared off for farmland. It’s a battle keeping the trees from overtaking this small piece of property. But the atmospheric CO2 concentration rise is slow and leisurely in comparison. The growth rate of forest density, and area when allowed, far outstrips the rate of CO2 rise, thus the increase in the effect I noted (FCA) should be happening.

Alexander Feht says:
June 6, 2011 at 10:31 pmI always wondered if agricultural cultivation of vast barren lands by man, going on for thousands of years, has ever been taken into account as an important CO2-absorbing and climate-moderating factor by those who, like IPCC and Dr. Ira Glickstein, are so fond of playing games with the formulas.

It may very well be that human activity, in the final reckoning, is more beneficial than it is destructive, as opposed to the purely hypothetical “natural state” of the planet.

I have wondered the same. Wheat and many other crops farmed on a very large scale are monocot grasses which have the C4 type of photosynthesis, more efficient than the Hatch-Slack C3 photosynthesis of dicot plants (e.g. trees). Therefore, if you clear forest for instance and replace it with a grass type agriculture, then the net result could well be more fixation of CO2 from the atmosphere, not less. (But turn it into a shopping mall and parking lot and thats another story.)

Thus agriculture globally is essentially a process of transferring atmospheric CO2 to human biomass. Thus if the extreme environmentalists were ever to realise their utopian agenda of human population reduction, it could have an unexpected outcome for atmospheric CO2.

Increased density of stocking, as several have commented here, isn’t all that it’s cracked up to be. I am a professional forester with 30+ years experience. Much of the increase in density of stocking in the US is due to the laissez-faire attitude of the USDA Forest Service, essentially walking away from management of more than 190 million acres of National Forest lands.

Increased density of stocking, up to a point, does indeed increase biomass and thus, carbon “sequestration.” However, these increases also lead to more decadent, fire prone forests (google Biscuit and B&B Fires in Oregon).

All trees require sunlight upon their leaves to actively conduct photosynthesis and grow. Dense forest has more shade and eventually, even shade tolerant species (true firs, hemlock, e.g.) begin to lose leaves and reduce growth. If this continues long enough, trees become stressed and much more prone to insects and diseases, and eventually, stand replacing fires. This is exactly the legacy that the policies of the USDA Forest Service is leaving – more and more over-mature, overly dense, decadent, and burned up forests, especially in the US West.

So, while some “researcher” may model on the computer that denser forests sequester more carbon, a simple math exercise, increased density if left to it’s own devices, is terrible for long term forest health.

Professor Pekka Kauppi of Helsinki University, a co-author of the study, said: ‘People worry about forest area, and that’s quite correct. But if you want to know the carbon budget, it cannot be monitored observing only the changes in area. It is more important to observe this change in forest density.’

Hasn’t Joe Romm been saying this very same thing about Arctic sea ice for years now? Funny how it’s come full circle to bite him in the ass now. How is the ice thickness doing now anyway?

This is a pet peve of mine. There’s a difference between a sink and a store. Once the forest reaches max biomass density it is no longer a significant sink. In fact, due to the actions of insects and decay, it produces methane as it consumes co2. So, a mature forest is not a good thing for ghg reduction. On the other hand, if there’s a big forst fire, then some of the carbon is converted into char, which is somewhat longer-lived in the soil.